Cultivate Causative Agent of Syphilis, T. pallidum in cell or organ culture. (1) Determine which factors prolong the survival of T. pallidum in vitro. (2) Develop rabbit testis cell and organ cultures grown under conditions of reduced oxygen. (3) Cultivate T. pallidum in rabbit testis cell and organ cultures and in human foreskin cell cultures grown under reduced oxygen or anaerobic conditions. (4) Determine by nucleic acid hybridization the genotypic relationship between cultivated treponemes and T. pallidum Nichols. (5) Idenify cultivated treponemes by fluorescent antibody strain techniques. (6) Determine whether cultivated treponemes are pathogenic for rabbits.